Though this is likely old hat to many of you, I thought this was worth passing along for folks new to Mavericks or to the sidebar.
Before Mavericks, to add a file to the Finder sidebar, you simply dragged it over and released it. Easy to remember, easy to perform. The down side was accidentally adding items to the sidebar. Not a big problem, but it’s happened to me.
With Mavericks, Apple changed the way this works. If you drag a file to the sidebar, you can drop it into a folder stored in the sidebar, but releasing the file won’t add it to the sidebar itself.
There are two ways to do this. You can hold down the command (⌘) key while you drag the file, then drop it where you want it. Alternatively, you can select the file in a Finder window, then either choose File > Add to Sidebar or type the keyboard shortcut ⌘-control-T. Hat tip to Kirk McElhearn for that last one.
Pass it along.